1. Field of the Invention
The present invention relates generally to a shaft coupling and, more particularly to a shaft coupling which comprises an elastomeric member in combination with a spline arrangement for transmitting torque between a drive shaft and an output shaft.
2. Description of the Related Art
Many different types of shaft couplings are known to those skilled in the art. It is sometimes beneficial to provide a compliant, or resilient, member between a drive shaft and an output shaft for the purpose of dampening vibration, reducing noise transmission through the coupling or permitting an articulation of the coupling arrangement. When a compliant or resilient member is used in this manner, it is well recognized that the compliant member does not possess the magnitude of strength that a metalic member can provide. Therefore, failure of the compliant member is possible. For this reason, a non-resilient device is sometimes used to provide a failsafe torque transmission component for use when, and if, the compliant member fails.
U.S. Pat. No. 4,406,640, which issued to Franklin et al on Sept. 27, 1983 discloses a drive axle assembly which comprises a drive shaft with an integral flange at one end and a second drive shaft with an integral hollow head at an end adjacent to the flange of the drive shaft. The flange and head are provided with cooperating lugs that form a lost motion positive drive device between the shafts. The drive axle assembly also includes a torsional damper that comprises a shell welded to the flange, a canister welded to the head and a pair of rubber bushings compressed between the shell and the canister. This assembly has an internal spacer to maintain longitudinal alignment of the shafts and a failsafe feature which retains the shafts together in the event the rubber bushings fail.
U.S. Pat. No. 4,516,956, which issued to Staiert on May 14, 1985, discloses a weld joint structure for an elastomeric flexible coupling. The weld joint structure is provided for a flexible coupling which has an inner hub, an outer cup and an elastomeric ring for torsional vibration protection of a drive train. The outer cup defines an integral radially inwardly disposed tubular portion which has an internal seat and an adapter member of different ferris material composition has an external seat that is connected to the cup by an annular weld joint. Although the device disclosed in this patent is primarily concerned with a weld joint structure, it shows the use of an elastomeric member which has an annular shape for connecting one shaft to another. It also shows the use of a spline arrangement to provide connection between one of the shafts and a member which is attached to that shaft, through the spline arrangement, and to a portion of the annular elastomeric member.
U.S. Pat. No. 2,154,077, which issued to Sampson on Apr. 11, 1939, discloses a universal joint assembly which includes a compliant connection between first and second portions of a coupling. This patent shows an elastomeric member disposed radially between a portion of a first rotatable member and a portion of a second rotatable member. A rubber ring is interposed between a pair of concentric driving and driven members for action in torsion in transmitting rotation between the coupled parts while yielding under stress to accommodate misalignment and relative axial and angular displacement of the shafts during operation.
Copending patent application Ser. No. 071,244 which was filed by Zeiser et al on July 9, 1987, discloses a concentric elastomeric shaft coupling for use with dual shafts that are disposed in coaxial and concentric relation with each other. The invention described in this copending application utilizes an elastomeric torque transmitting member in conjunction with a spline arrangement which is configured to transmit torque when the compliant member deforms and relative rotation occurs between the input and output shafts of either an inner drive arrangement or an outer drive arrangement. This deformation occurs when the magnitude of torque between input and output shafts exceeds a predetermined value. The spline arrangement disclosed in this copending patent application also serves to provide a failsafe torque transmitting component which is operative in the event that the compliant member fails during operation.